The present invention relates to an electronically detectable resonance label, in particular an RFID label, with a substrate made of plastic foil and with conductive surfaces on the front and rear of the substrate, with some of the conductive surfaces forming a capacitor in a mutual area of overlap, comprising a first capacitor plate on the front of the substrate and a second capacitor plate on the rear of the substrate.
Such resonance labels are well known, as can be seen for example from WO 89/05984. The known labels are made in a continuous process, using runs of metal-coated plastic foil, with the pattern of the conductive tracks being generated on both sides of the substrate by using etching technology, and prior to etching being deposited with photo technology. It is understood that both on the front and rear of the foil run, the conductive tracks have to be aligned in a certain position in relation to each other.
It is the object of the present invention as characterised in the claims, in the case of resonance labels of the type mentioned in the introduction, to ensure that the capacitor always has the same capacity, even if during the production process, the conductive tracks on the front and the rear of the substrate are somewhat offset in relation to each other. According to the invention, this object is met in that the capacitor plates are in the shape of elongated strips of uniform width along their entire length; in that they only partially overlap; and in that the area of overlap is arranged at a distance from both ends of at least one capacitor plate
Preferably, the area of overlap is arranged at a distance from both ends of both capacitor plates. In this way, there is the possibility of relative displacement in two directions.